Lip is sleeping with Mandy while she is pretending to be Ian's girlfriend to hide the fact that he is gay. However, after Mandy falls pregnant with Lip's baby, everyone begins to think the child is Ian's, so the Maguire family welcome him into the family with the threat of castration if he and Mandy do not marry. When Ian announces their engagement, the Gallaghers and Maguires throw a party at The Jockey, but a revelation from Lip turns the happy occasion into an evening of chaos and bloodshed. Meanwhile, Frank is left debt-ridden by Cassie Weston (Moya Brady), The Jockey's new landlady. He must come up with a way to pay back his years of free booze. Unfortunately for him, she might have just the solution. But their plan is foiled by a devious Karen. Elsewhere, Sheila cold-turkeys her tablets, leaving her convinced that the twins are monsters, while a late-night encounter with a tearaway teenager brings a new man into Fiona's life.